Deicer for aeroplanes



c. w. LEGUILLON 1,942,867 DEIGER FOR AEROPLANES Filedua 17, 1932 Jan. 9,1934.

DUE-27.7275

Uieyuz/bn 7- I if! 5 Patented Jan. 9, 1934 umreo STATES DEICER FORAEROPLANES Charles W. Leguillon, Akron, Ohio, assignor to The B. F.Goodrich Company, New York, N. Y., a corporation of" New YorkApplication May 17, 1932. Serial No. 611,785 3 Claims. (01. 244-31) Thisinvention relates to devices for preventing accumulation of ice uponaeroplanes or the like and its chief objects are effectiveness andeconomy and simplicity of construction and operation.

Of the accompanying drawing:

Fig. 1 is a perspective view of an aeroplane equipped with anembodiment-of my invention in its preferred form.

Fig. 2 is a section on line 2-2 of Fig. 1, with certain air-bagsconstituting parts of the embodiment in collapsed condition.

Fig. 3 is a section on line 22 of Fig. 1 with the air-bags in distendedcondition.

Referring to the drawing, the device in the preferred form here showncomprises 'an extensible sheet-1O of material such as vulcanized rubberor rubberized, stretchable fabric extending about the leading edge ofthe wing or part to be protected and having its margins anchored to theupper and lower faces of the wing respectively as by stud members 11, 11extending through apertures in the sheet 10, provided with respectivecotter pins 12, 12, and secured to the wing by screws 13, 13 (Fig. 3).

Underlying the sheet 10 just above and below the middle horizontal lineof the leading edge of the wing, between the sheet 10 and the wing, arerespective bags 14, 15' extending lengthwise of the wing and havingcommunication through conduits 16, 1'7 with fluid-pressure andevacuating means adapted to distend the bags periodically, either inalternation or simultaneously, and to exhaust them to permit them tocollapse. For simplicity and economy of construction and effectivenessin operation the bags preferably are not adhered to the sheet 10. 4

The bags preferably are formed of rubber and reinforced with fabric toprevent them from ballooning locally and they preferably are mountedupon and vulcanized to a rubberized fabric base 18 common to them andsecured to the wing along its middle line by screws such as the screw Inthe operation of the device the distension and collapsing of the tubes14, 15 causes a stretching and retraction of the sheet 10 and consequentbreaking up and dislodgment of ice forming thereon, and by varioustiming of alternate and simultaneous distension of the bags varying andhighly effective stretching of the sheet 10 may be obtained.

Preferably the sheet 10 has mixed therein or applied thereto a substanceadapted to exude from .the pores of the rubber, especially at lowtemperature, and form a surface film thereon adapted to lessen theadhesion of ice to the surface of the sheet.

The water-repellent material to be used for impregnating the rubberpreferably is a liquid and the liquid to be used for this purpose shouldbe one which has a freezing point below the iceforming temperatures andwhich is fluid at these temperatures. It should be of low viscosity atthese temperatures and should not be sticky, and hence adhesive towardice. It should also be material which will be absorbed into the rubber,but which will not swell or weaken the rubber to such an extent that itwould have insuflicient tensile strength for the use to which it isapplied. It is also important that the liquid be of relatively highboiling point in order that it may not evaporate from the surface at thehigh temperature to which it may be subjected.

It is desirable that the liquid be such that it may be applied'to therubber without substantially-deteriorating the rubber surface; that itwill reduce the adhesion of the ice to the surface and yet will notevaporate from the surface at ordinary temperatures; that the rubberwill have a substantially dry surface at ordinary temperatures; and thatit will exude from the rubber at ice-forming temperatures.

A large number of oils are absorbed into vulcanized rubber, butordinarily with the result that the rubber is thereby caused to swell toa greater or less extent and consequently its tensile strength and otherphysical properties are more or less weakened. Because of this effect ithas been generally considered to be undesirable to use most oils incontact with rubber.

I have found that by mixing with an oil which will be absorbed into therubber surface and give the desired lubricating or non-adhesivecharacteristics, a liquid which is insoluble in the rubber and whichwill prevent swelling thereof, a composition will be producedwhich willgive the desired surface and which will not substantially BoilingFreezing point point Tetrahydronaphthaleno-. Dekahydronaphthalene 176: 5Above 300 The addition of one of these liquids to vulcanized rubberwill, however, cause the rubber to swell and will decrease its tensilestrength. By adding a liquid such as diethyl'phthalate or butyl tartrateto one of the above oils, the swelling of the rubber and the decrease intensile Above 250 As an example of a suitable composition to be,

applied to a rubber surface, and which will reduce the adhesion of iceto the rubber surface, the following substances may be mixed in theproportions stated:

Parts by 1 volume Pine oil 4 Diethyl phthalate 4 Castor oil 1 Thisparticular mixture has the added advantage that its solubility in rubberis reduced at the ice forming temperatures, so that at thesetemperatures it will exude from and render the surface well lubricatedwhile it will produce a substantially dry surface in the rubber atordinary temperatures.

When this mixture is applied to a vulcanized rubber of the compositionhereinafter described for use in preventing the accumulation of ice uponaircrafts, the oil will exude from the surface at the ice formingtemperature and replace any oil which may be removed from the surface bythe air forces, by vaporization or by removal with the ice. Additionaloil may be applied from time to time as the supply is exhausted. When aneutral oil which does not radically alter the physical properties ofthe rubber is absorbed in rubber the rubber is actually preservedagainst oxidation.

Any rubber mixture, capable of satisfactory vulcanization, may be usedfor producing the rubber surface, the following typical mixture beinggiven as an example of such a composition:

Parts Smoked sheet 100 Zinc oxide 10 Sulfur 3 Accelerator -r 1 When theoilis added to the vulcanized rubber to reduce the adhesion of ice tothe surface, the rubber mixture should be one, such as the above, withlittle or no oil soluble sticky material that would render the surfaceadhesive to ice. Some other colloidal surface may be used in place ofrubber, if the surface is to be one that is devoid of irregularitiesinto which water might penetrate and, upon freezing, anchor itself.

When a vulcanized rubber of the above described composition is soaked inpure pine oil for 24 hours, its average increase in volume will 'begreater than 50%, and its average decrease in tensile strength will begreater than 75%. However, when a vulcanized rubber of the samecomposition is soaked for 24 hours in the mixture of oils referred toabove, it was found to have an increase in weight of about 19%, anincrease in gauge or volume of about 7 /2% and an average decrease intensile strength of about 12 /2%. It is apparent, therefore, thatalthough an appreciable weight 'of oil had been absorbed into therubber, the volume had been only relatively slightly increased and thetensile strength had been but moderately affected.

Although I have described a particular mixture of liquids, it is notintended to thereby limit the invention to the specific liquids orproportions mentioned. Other vegetable, mineral or synthetic oils may beused to give the desired lubricating or reduced adhesioncharacteristics. Other liquids than those described may also be added tosuch oils to reduce the swelling of the rubber and the resultantdecrease in tensile strength and deterioration of other physicalproperties. Such liquids may be alcohols, ketones and other esters whichpossess the property of mixing with nitrocellulose or, as hereinbeforeindicated, castor oil. The boiling point and freezing point may beunimportant in the particular use to which the liquids may be applied,in which event a wide range of selection may be had. Furthermore theparticular oil added for this purpose may not come within the range -oftemperatures desired, although the resultant mixture may be within thatrange. p Modifications are possible within the scope of the invention asdefined by the appended claims.

I claim:

1. In combination with a member exposed to ice-forming conditions, astretchable sheet and a flexible bag so associated therewith as tostretch the sheet, to a greater extent than the wall of the bag isstretched when thebag is distended from 115 a flattened to a morerounded form, and means for modifying the pressure of fluid within thebag. I

2. In combination with an aerofoil, a stretchable sheet of materialextending about the leading edge of the aerofoil, and secured thereto atpositions rearward of the leading edge, a flexible bag mounted betweenthe aerofoil and the said stretchable sheet, and means for modifying thepressure of fluid within the bag for changing its shape, the sheethaving unattached zones and the construction'and association of thesheet and the bag being such that the sheet is stretched to a greaterextent than the wall of the bag when the bag is changed from a flattenedto a more rounded form.

3. A combination as defined in claim 2 including a plurality of the bagsfor non-symmetrical, alternating distortion of the sheet and definingmore than two freely stretchable zones of the 135 sheet.

CHARLES w. LEGUILLON.

